This paper presents a characterization of the following dry granular materials: soya, colza and rye seeds. The physical properties of the grains and the materials are useful for characterizing the materials' behaviour during flow, while the external conditions (consolidation) determine storage and handling conditions. The physical properties of the grains (specific densities) and of the materials as a whole (compacity or porosity, and critical angles) were measured. The flow functions were determined by modified shear box testing. Then the internal friction angles and the flowability index for each granular material were obtained. Indeed, the behaviour of a flowing granular material results from these two groups of factors and is characterized by the flowability, which is the ratio of highest consolidation stress and unconfined yield strength. In practice, the flowability index is used to classify materials, so that the larger the flowability index, the smaller the bulk solids strength will be in relation to the consolidation stress, and therefore the higher the flowability of the bulk solid.